Local Electronic Structure in AlN Studied by Single-Crystal (27)Al and (14)N NMR and DFT Calculations

Both the chemical shift and quadrupole coupling tensors for [Formula: see text] N and [Formula: see text] Al in the wurtzite structure of aluminum nitride have been determined to high precision by single-crystal NMR spectroscopy. A homoepitaxially grown AlN single crystal with known morphology was used, which allowed for optical alignment of the crystal on the goniometer axis. From the analysis of the rotation patterns of [Formula: see text] N ([Formula: see text]) and [Formula: see text] Al ([Formula: see text]), the quadrupolar coupling constants were determined to [Formula: see text] kHz, and [Formula: see text] MHz. The chemical shift parameters obtained from the data fit were [Formula: see text] ppm and [Formula: see text] ppm for [Formula: see text] N, and (after correcting for the second-order quadrupolar shift) [Formula: see text] ppm and [Formula: see text] ppm for [Formula: see text] Al. DFT calculations of the NMR parameters for non-optimized crystal geometries of AlN generally did not match the experimental values, whereas optimized geometries came close for [Formula: see text] Al with [Formula: see text] MHz, but not for [Formula: see text] N with [Formula: see text] kHz.